webtrees is the web's leading on-line collaborative genealogy application. It is open source software, and costs $ zero - yes, that means totally FREE!
All you need to use it is a website with PHP and MySQL installed.
It works from standard GEDCOM files, and is therefore compatible with every major desktop application; and it aims to be efficient and effective by using the right combination of third-party tools, design techniques and open standards.

Maps :
View maps of the locations where your ancestors lived and worked, using the Google Maps™ feature.

Themes (templates) :
The standard webtrees package comes with six style themes (templates) from which to choose. One of those ("colors") has no less than 14 (!) different "color palettes", giving you a total of 19 different styles for your webtrees site. You can choose a different one for each family tree, and even allow your users to choose their own.

International display :
By default webtrees is displayed in "International English", but you can choose to install many other languages. These already include US, British, and Australian English, Italian, Polish, Spanish, Finnish, French, and German. Others, including Catalan, Danish, Dutch, Estonian, Hebrew, Hungarian, Norwegian, Russian, Slovak, Slovenian, Swedish, and Turkish are well developed, and more will be available later.